1. Field of the Invention
The present invention relates to a loudspeaker case structure for video display appliances. In particular, the present invention relates to a loudspeaker case structure for video display appliances which can absorb and dampen vibrations arising from the output of a loudspeaker and thus remove the howling phenomena produced due to the transfer of the vibrations directly to a cathode-ray tube, by improving the fastening structure of the loudspeaker.
2. Description of the Prior Art
Video display appliances such as monitors, televisions, etc., are typically provided with a cathode-ray tube (CRT). Such video display appliances are also provided with at least one loudspeaker for the output of sound.
FIG. 1 is a sectional view illustrating the structure of a conventional video display appliance in which a loudspeaker is installed. Referring to FIG. 1, a lug 3 of a CRT 2 is fastened to a cabinet boss 5 by a fastening screw 4 to fix the CRT 2 to a cabinet 1. Also, a loudspeaker 6 is fastened to another cabinet boss 8 by a fastening screw 7 to fix the loudspeaker 6 to the cabinet 1. Preferably, a plurality of loud speakers 6 may be installed in predetermined positions of the cabinet 1 to cause a surround-sound effect.
In the conventional video display appliance as constructed above, a video signal is displayed on the CRT 2, while a sound signal is outputted by the loudspeaker 6.
The sound waves produced from the loudspeaker 6 are composed of vibration components, and such vibrations are directly transferred to the CRT 2 through solid state media in the cabinet 1. This causes the howling phenomena to be produced on the screen of the CRT 2.
Specifically, in the event that the sound produced from the loudspeaker 6 becomes louder or several loudspeakers are provided in the video display appliance, greater vibrations are generated to intensify the howling phenomena produced on the screen of the CRT 2.
According to the conventional video display appliance, the CRT 2 and the loudspeaker 6 are directly fixed to the cabinet 1 to form a single bodied frame structure, and thus the vibrations produced from the loudspeaker 6 are not suppressed, but are directly transferred to the CRT 2.
Specifically, the vibrations produced from the loudspeaker 6 are transferred to the cabinet 1 through the screw 7 and the boss 8, and then are transferred to the CRT 2 through a cushion portion 1a of the CRT 2.
On the other hand, the vibrations produced from the loudspeaker 6 are also transferred to a panel 2a of the CRT 2 through another path composed of the boss 5, screw 4, and lug 3, and then to a shadow mask 2c through a frame 2b. At this time, three electron beams for red, green, and blue colors, which are emitted from electron guns 2d, are directed to the fluorescent screen of the CRT 2 through beam-passing apertures provided in the shadow mask 2c. If the vibrations are transferred to the shadow mask 2c through the frame 2b, the electron beams, which are emitted to the fluorescent screen of the CRT 2 through the beam-passing apertures of the shadow mask 2c, are affected by the transferred vibrations, thereby producing the howling phenomena on the display screen of the CRT 2.
The howling phenomena deteriorates the picture quality and the reliability of the appliance. Also, it fatigues the user's eyes easily.